1. Field
Exemplary embodiments of the present invention relate to methods for fabricating a nonvolatile memory device, and more particularly, to methods for fabricating a three-dimensional (3-D) structured nonvolatile memory device in which a plurality of memory cells are stacked over a substrate in a vertical direction.
2. Description of the Related Art
A nonvolatile memory device retains stored data although the power is not supplied. A variety of nonvolatile memory devices, such as flash memory, are being widely used.
As the improvement of the degree of integration of two-dimensional (2-D) structured nonvolatile memory devices with memory cells that are formed over a semiconductor substrate in the form of a single layer has reached the limit, there has been proposed a 3-D structured nonvolatile memory device in which a plurality of memory cells is formed along channel layers in a vertical direction over a semiconductor substrate. More particularly, the 3-D structured nonvolatile memory device includes a structure in which charges are stored in floating gate electrodes made of a conductive material and a structure in which charges are stored in charge trap layers made of an insulating material.
In conventional art, charge trap layers are formed across a plurality of memory cells along a channel layer during a manufacturing process. For this reason, charges trapped to store data may be spread nearby along the charge trap layers, which may deteriorate the reliability of a nonvolatile memory device.